Interrelationship of endocrine glands under thermal stress: effect of exogenous glucocorticoids on mineral, enzyme, thyroid hormone profiles and phagocytosis index of Indian goats.

OBJECTIVE

The purpose of the investigation was to examine the pineal-adrenal-thyroid-immune axis in female goats under short-term heat stress. The study was conducted to observe the influence of glucocorticoids on biochemical, endocrine profile and non-specific immune response in propranolol treated goats.

METHODS

Melatonin and glucocorticoid secretions and several other endocrine and biochemical blood parameters reflecting the animals well being were determined over a one week period after goats had been exposed to 40 degrees C and 60% relative humidity for 17 days. Chemical pinealectomy was achieved using propranolol followed by exogenous hydrocortisone treatment. This treatment continued from day 11 to day 17 of the study. Blood samples were drawn on day 10 to assess heat stress effect and twice daily after each treatment from day 11 to 17 to find the effect of hydrocortisone on various parameters studied.

RESULTS

Thermal stress significantly (P <or= 0.05) affected the levels of plasma calcium, ACP, ALP, T3, T4 and phagocytosis index. Chemical pinealectomy significantly (P <or= 0.05) affected plasma levels of the parameters studied and these could be significantly (P <or= 0.05) counteracted by administration of hydrocortisone to varying levels. Chemical pinealectomy aggravated thermal stress; although administration of hydrocortisone could ameliorate the condition.

CONCLUSIONS

The data generated from the study help us to understand the functional relationship between pineal, adrenal and immune system, and how this relationship modifies the biochemical, endocrine and non-specific immune response for the well being of the goats under thermal stress.